Mascara brush



FIG. 1 is a front view of a mascara brush according to the new and ornamental design;

FIG. 2 is a top view thereof;

FIG. 3 is a side perspective view thereof;

FIG. 4 is a side view thereof; and,

FIG. 5 is a bottom view thereof. 

CLAIM The ornamental design for a mascara brush, as shown and described. 